Microbes Make Us Sick
Microbes live everywhere on Earth. They can be found in food,
air, soil, water, saliva, a doorknob or hypodermic needles. But
once inside our bodies, some microbes can make us sick.
Viruses can make us sick when they infect our cells and turn
them into virus factories. Bacteria, protozoa and fungi regularly
live harmlessly in and on the body. But sometimes, these microbes
start colonies in areas of the body where theyre not used to
living. That makes us sick. Other times, normally harmless bacteria
produce poisons. Those poisons kill cells and cause illness.
How the Body Defends itself Against Illness
Our bodys immune system has many defense weapons to fight
Skin is our first line of defense. This tough barrier
keeps most microbes from entering our bodies.
Our stomach and intestines produce strong acids and
enzymes that kill most of the microbes that we swallow.
One of the tasks carried out by special molecules called hormones
molecules are the smallest unit of matter, formed by groups of
atoms is to stir up and deploy our immune system forces.
Antibodies are the immune systems advance scouts. They
are Y-shaped molecules that travel through the body looking for
invading microbes. When they find them, they grab them and disable
White blood cells are the immune systems big guns.
Alerted by antibodies, they track down the invading microbes
and destroy them.
Invading microbes produce negative effects, but our immune
system defenses also cause symptoms of disease. For example,
the stuffy nose and sneezing of the common cold is a result of
the immune system flooding the area with potent microbe-fighters.
The symptoms tell us that a cure is on the way.